1. Field of the Invention
This invention relates to a rubbery marine fender, and more particularly to an improvement of a rubbery buckling-type marine fender such as hollow cylindrical marine fender, V-shaped marine fender or the like absorbing energy in the berthing of a vessel and causing a buckling phenomenon during compression deformation.
2. Description of Related Art
There has hitherto been used a rubbery hollow cylindrical marine fender of a conical trapezoidal form as shown in FIG. 1. This marine fender comprises a main cylindrical rubber portion 12, a securing flange portion 13 for a quay wall, a shock receiving portion 14 and iron plates 15, 16 embedded in the portions 13, 14. When such a marine fender is compressed in its axial direction by berthing a vessel or the like thereto, there is obtained a deflection-reaction force curve absorbing a berthing energy as shown in FIG. 2. As seen from FIG. 2, after the reaction force increases with the increase of deflection to arrive at an upper peak (point A), it decreases to arrive at a point C though deflection increases, and again rapidly increases with further increase of deflection.
In the marine fender exhibiting such a characteristic curve, the actually usable range is a deflection range from the reaction force at the point A to a point B showing the reaction force equal to the point A, in which the absorption energy of the marine fender is represented by an area defined between the deflection-reaction force and an abscissa up to the point B. However, the reaction force is actually decreased to the point C, so that absorption energy is lost only by a portion S corresponding to an area surrounded with a dotted line A-B and a curve A-C-B.